Sika has long been considered a world leader in the innovation and production of concrete admixtures. Now Sika has identified environmental trends that are predicted will change the needs for concrete products in the future.
These selected challenges and the appropriate Sika solutions are:
Energy efficiency – Sika Concrete Admixtures and Systems contribute to reduce the energy demand of the concrete mix design and its application.
Resource efficiency – Sika Concrete Admixtures and Systems contribute to reduce the resource demand of the concrete mix design.
Climate protection – Sika Concrete Admixtures and Systems contribute to reduce the carbon emissions of the concrete mix design.
Water efficiency – Sika Concrete Admixtures and Systems contribute to reduce the water demand required to achieve its quality and improve the durability of concrete.
Concrete admixtures can improve the its sustainability in many different ways: Firstly, by improving the quality and its performance significantly, which, in return, extends its service life. In addition, thanks to the use of admixtures, the application of concrete instead of other building materials can improve the life cycle of infrastructures; for example, concrete roads greatly improve the quality and durability of highways for main traffic arteries compared with conventional road surfacing.
Further, the addition of special admixtures, such as stabilizing or water reducing admixtures, also enables the use of alternative and recycled materials, such as recycled aggregates, for the production of good quality concrete. Finally, in many cases the energy required to produce certain cement or concrete mixes will be positively impacted with the use of admixtures.
One example is the addition of water reducing and accelerating admixtures to obtain high early strengths in precast concrete, to greatly reduced or even completely replaced external heating of elements.
Sika Sustainable Concrete System Components
1. Durability
Several admixtures will allow for the production of concrete with extended durability in regular circumstances or even in a severe environment. For example, Sika® ViscoCrete® minimizes porosity in the cement matrix significantly and SikaAer® improves freeze/thaw resistance of concrete.
2. Solution
The use of the right admixtures allows for the production of specialty concrete, which offer environmentally friendly applications or can be used instead of other building materials (e.g. pervious concrete, insulating type). Sika® ViscoCrete® – Self Compacting Concrete (SCC) enables the reduction of a structure’s dimensions (wall thickness); Sika® Stabilizer – generates a stable paste layer around the aggregates; and SikaPlast® – ensures a high quality paste.
3. Source
Using alternatives of recycled materials in a concrete mix often has a negative impact on the fresh or hardened properties. Admixtures can be used efficiently to counter such effects. SikaPlast® and Sika® ViscoCrete® ensure the use of concrete produced with recycled aggregates, and SikaRapid® compensates for the loss of early strength by using SCM.
4. Energy
A lot of energy is used in the production, placement and/or curing of cement and concrete.
Several admixture and additive solutions allow for a reduction of this process energy. Sika® ViscoCrete® or SikaPlast® offset the negative influence on final strength of the cement reduction through water reduction; SikaGrind® reduces of time to grind cement of a specified fineness; and SikaRapid® allows for a reduction of steam curing in precast element production.
Case study: Paste Volume Optimized Concrete with Sika® ViscoCrete®
Argos is the first cement and concrete producer in Colombia and the fourth largest concrete producer in the USA. Argos Quality Control and Concrete Technical Development collaborated with Sika’s Technical Department in a challenge to further reduce water and cement (paste) content in high volume concrete.
The focus of their strategy was to incorporate the latest aggregates compressible packing model, but to use a less viscous cement paste and to include SikaViscocrete. The Viscocrete technology enabled a reduction of the cement paste contents in the conventional concrete, thereby obtaining a better quality concrete (in fresh and hardened states) and at a lower cost.
The durability aspects of the cement paste reduction (for a constant w/c ratio) were studied in detail. It was found that lower paste cement content was able to decrease four of the major challenges in production, namely: the drying shrinkage, creep, abrasion erosion and liquid penetration (chlorides and sulphate penetration).
Argos was able to take advantage of these new admixture technologies, thereby managing the production of better concrete, using less water and cement, while still maintaining or improving its properties. Apart from economic benefit, this company, whose manufacturing priority is sustainability, produces a smarter and more sustainable concrete.
This paste volume optimization program has been introduced in all of Argos’ main centres of operation in Colombia, including Bogota, Medellin, Barranquilla, Cartagena and Cali. Following extensive laboratory trials, the field-testing phase was initiated and successfully completed.
Based on existing recipes for all Argos concrete varieties the target was:
• To optimize costs of recipes
• To ensure no negative influences on fresh properties
• To improve the quality of hardened concrete
• To increase the recipe for sustainability
